The objective of this study is to examine the cancer mortality experience in the United States relative to cancer etiology. Special emphasis is placed upon the selection of areas in the U.S. for intensive study. Publications from this area of interest have facilitated the design of ongoing analytical investigation to test specific etiologic hypotheses. An analysis of prostatic cancer mortality rates suggested that environmental exposure related to urban living may account for the predisposition of American blacks to this tumor. Respiratory cancer mortality, 1950-69, was consistently high in U.S. counties where shipyards were engaged in the construction and repair of large naval and cargo vessels during World War II. When cell types of leukemia for 1968-71 were analyzed, some clustering of acute myeloid leukemia was seen in the central United States. Ethnic susceptibility appears to account, at least in part, for the regional clustering of kidney cancer and may provide leads to environmental determinants. We are continuing to expand our data sets, both of reported deaths and measures of exposure.